Sex-related differences in aging rate are associated with sex chromosome system in amphibians

Sex-related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of capture-recapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed that the strength and direction of sex differences in aging rates (and not lifespan) differ between XY and ZW systems. Sex-specific variation in aging rates was moderate within each system, but aging rates tended to be consistently higher in the heterogametic sex. This led to small but detectable effects of sex chromosome system on sex differences in aging rates in our models. Although preliminary, our results suggest that exposed recessive deleterious mutations on the X/Z chromosome (the "unguarded X/Z effect") or repeat-rich Y/W chromosome (the "toxic Y/W effect") could accelerate aging in the heterogametic sex in some vertebrate clades.Peer reviewe

Spatial scales for the management of amphibian populations

Conservation programs must be based on a detailed knowledge of the distribution of communities and populations, but this changes with the spatial scale of observation. In this context, we examined the multiscale patterns of spatial variation of a montane amphibian assemblage in Central\ud Spain. The largest spatial scale examined (in a range of 1200 m) accounted for the maximum variability in both species richness and larval abundance, while the smallest scale examined (pond) was responsible for the maximum variation of larval abundances of many individual species. Habitat characteristics seemed to be more related to spatial variation of the amphibian assemblage at a particular spatial scale (in a range of 75 m), and distances among ponds were in part responsible for variation of larval abundance, but not species richness

Determinants and Consequences of Dispersal in Vertebrates with Complex Life Cycles: A Review of Pond-Breeding Amphibians

International audienc

Coevolution between MHC class I and antigen-processing genes in salamanders

Proteins encoded by antigen-processing genes (APGs) provide major histocompatibility complex (MHC) class I (MHC-I) with antigenic peptides. In mammals, polymorphic multigenic MHC-I family is served by monomorphic APGs, whereas in certain nonmammalian species both MHC-I and APGs are polymorphic and coevolve within stable haplotypes. Coevolution was suggested as an ancestral gnathostome feature, presumably enabling only a single highly expressed classical MHC-I gene. In this view coevolution, while optimizing some aspects of adaptive immunity, would also limit its flexibility by preventing the expansion of classical MHC-I into a multigene family. However, some nonmammalian taxa, such as salamanders, have multiple highly expressed MHC-I genes, suggesting either that coevolution is relaxed or that it does not prevent the establishment of multigene MHC-I. To distinguish between these two alternatives, we use salamanders (30 species from 16 genera representing six families) to test, within a comparative framework, a major prediction of the coevolution hypothesis: the positive correlation between MHC-I and APG diversity. We found that MHC-I diversity explained both within-individual and species-wide diversity of two APGs, TAP1 and TAP2, supporting their coevolution with MHC-I, whereas no consistent effect was detected for the other three APGs (PSMB8, PSMB9, and TAPBP). Our results imply that although coevolution occurs in salamanders, it does not preclude the expansion of the MHC-I gene family. Contrary to the previous suggestions, nonmammalian vertebrates thus may be able to accommodate diverse selection pressures with flexibility granted by rapid expansion or contraction of the MHC-I family, while retaining the benefits of coevolution between MHC-I and TAPs.The work was supported by the Polish National Science Centre (Grant No. 2016/23/B/NZ8/00738) to W.B. D.J. was supported by PROTEUS project in Croatia; E.J. was supported by the University of Connecticut Research Foundation; M.Ma. was supported by a KAKENHI Grant-in-Aid for Young Scientists (B) (No. JP16K18613) from the Japan Society for the Promotion of Science; M.Mi. was supported by the Foundation for Polish Science (FNP) START stipend and the Polish National Science Centre Sonatina 3 (Grant No. 2019/32/C/NZ8/00440); J.V. was supported by Project No. KH130360 implemented with the support provided from the National Research, Development and Innovation Fund of Hungary, financed under the KH_18 funding scheme; B.Wa. was funded by the National Research Foundation of Korea (Ministry of Education, 2015R1D1A01057282); Ministry of Science, ICT, and Future Planning (2018R1A2B6006833).Peer reviewe